A method for measuring the oxygen consumption of intact cell monolayers

This report describes an open-air method for measuring the O(2) consumption (Q) over dot O(2)) of intact monolayers of cultured cells. This method is based on Fick's second law of diffusion. It requires only a micromanipulator and a miniature O(2) electrode to measure the Po(2), gradient in the culture medium in the well. It was compared with the conventional oxygraph chamber method. Both methods gave the same value for (Q) over dot O(2) in freshly isolated rat type II cells: 166 +/- 15.3 nmol . h(-1). 10(6) cells(-1) for the open-air method and 151 +/- 11.6 nmol . h(-1). 10(6) cells(-1) for the oxygraph chamber method (n = 11 experiments). But the open-air method gave significantly larger values for (Q) over dot O(2) in cells cultured for 2 days (236 +/- 8.8 nmol . h(-1). 10(6) cells(-1)) than the oxygraph method (71 +/- 15.2 nmol . h(-1). 10(6) cells(-1); P < 0.001; n = 12 experiments). This suggests that the way cells are detached from their substratum to be placed in the oxygraph chamber affects their Q (2). The open-air method may be useful for studies on the metabolic properties of monolayers because the cells do not risk being damaged.